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Bellyache Mountain SL 15° Long Big Agnes

Item Code: BTMBMSLLL13

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Bellyache Mountain SL 15° Long Big Agnes

Bellyache Mountain SL 15° Long Big Agnes: Mummy shape and lightweight materials will get you anywhere fast and dry.

Bellyache Mountain SL 15° Long Big Agnes Specs:

  • Left zip only
  • Size: Fits up to 6'
  • 700 DownTek/Fill Weight: 23oz
  • Bag Weight: 2lb 10oz
  • Girth: Shoulder 62"/Hip 56"/Foot 38"
  • Stuff Sack Size: M-8"x17.5" / Compressed Bag Size: 8.5"x8.5"
  • Color: Blue/Grey
  • Pad Size: Any

Bellyache Mountain SL 15° Long Big Agnes: Traditional Mummy bags are built for performance. In the first diversion from the Big Agnes System since they started 12 years ago, Big Agnes is proud to introduce the most technical old-school sleeping bags ever! These bags are insulated with DownTek™ water repellent down and constructed with Insotect Flow™ patented technology.

Bellyache Mountain SL 15° Long Big Agnes: Traditional style mummy shaped bags designed without the integrated pad sleeve. Mesh storage sack & nylon stuff sack included.70"/178cm YKK #8 zipper will mate together left and right zip bags. Interior fabric loops for sleeping bag liners.
Bellyache Mountain SL 15° Long Big Agnes: Insotect Flow™ is a flow-optimized insulation system that delivers uniform heat distribution and natural body contouring through its revolutionary baffle design. No-draft collar, no-draft wedge and no-draft zipper tube keeps cold air from sneaking in.

Big Agnes website


In stock items will ship within the next business day. Available item(s) is/are available to order. Most available items will ship within 9 business days, sometimes the process is faster and of course it will ship to you ASAP. There might be some exceptions, example: supplier is out of stock or manufacturing delays. If you have any doubt your item is in stock please call us at 303-984-4649.

For shipping rates and/or international shipping rates and policies, please click here.



If you placed an order at 123Mountain and you don't like it just send it back for a refund, applicable for the item not shipping costs*. Ship it back and as long as your item is in unused condition with original tags, boxes, etc.  Please follow the steps at Return Policy Page.

No returns on sale / promotional / discounted item(s).

* Even if the shipping was free we paid the carrier for the service provided and we will deduct $7.95 for Economy, $12.95 for Ground, etc.



Not stoked on your gear? Looking to return it? No problem, we have an Unlimited Return Policy as long as item(s) is/are in UNUSED CONDITION. We try to guarantee complete satisfaction with unlimited lifetime returns. If at any time - now, next month, in 30 years - you're not 100% satisfied, send your gear back for a refund. No questions asked. Check out Return Policy Page here. No returns on sale / promotional / discounted items, though.


We need your help to always make sure 123Mountain has the best prices! You may even benefit in the process. If you find an identical product at a lower price and in stock through another online site we will refund two times the difference.

Here's how it works:
•    Place the order on at our current price.
•    Email us within 24 hours that you are requesting a price match, including a link to the site where you saw the lower price.
•    We will adjust the price and take care of your refund.

For further information please go to 100% SATISFACTION page.


We offer three types of membership; Elite, Premium and Standard. Each membership group has fantastic advantages everything from store credit to an extra 10% OFF and FREE shipping.

Find out more which membership level that fits you the best, click here.

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